This application is designed to provide the candidate with support to continue his development as an independent physician-scientist with sufficient protected time to pursue his research in gene discovery and to provide mentorship to trainees. The candidate is Professor of Pediatrics and Human Genetics at the Mount Sinai School of Medicine. He is a board-certified pediatric cardiologist with expertise in the genetics of cardiovascular disease. His molecular genetics laboratory studies two autosomal dominant disorders with heart defects for which he has identified disease genes. Char syndrome, which has a phenotype that includes patent ductus arteriosus, is caused by transcription factor AP-2beta dominant-negative mutations. Noonan syndrome (NS), a pleiomorphic disorder with various cardiovascular abnormalities, is caused by gain-of-function defects in PTPN11, which encodes the protein tyrosine phosphatase SHP-2. The candidate has also discovered that similar PTPN11 mutations underlie other disease phenotypes, including certain myeloid disorders. In the proposed research, the candidate intends to test the hypotheses that PTPN11 mutations are associated with NS, with CHD other than pulmonic stenosis, as well as with non-syndromic CHD. NS cohorts with other anatomic subtypes and cohorts of subjects with only certain forms of CHD will be assembled and genotyped. The candidate expects that PTPN11 mutations causing sporadic CHD will be relatively milder and will be incompletely penetrant. It is also hypothesized that PTPN11 mutations alter phosphotyrosyl-binding domains cause NS by prolonging activation of SHP-2, that specific SHP-2 mutants causing LEOPARD syndrome will have greater gain-of-function than observed among classic NS mutants, and that mutations causing isolated CHD will result in less gain-of-function. To test these ideas, mutant SHP-2 proteins will be expressed in eukaryotic cells and tested for phosphatase activity, docking, as well as mitogen-activated protein kinase activity. The candidate hypothesizes that other genes altering the RAS-MAP kinase pathway also cause NS. He will document this through studies of signal transduction in skin fibroblasts derived from NS patients with and without PTPN11 mutations. Next, a candidate gene approach will be used to identify additional NS gene(s). This will be coupled with the use of human multiplex NS kindreds without PTPN11 mutations.